1. Field of the Invention
The present invention relates to a semiconductor device.
2. Description of the Related Art
Recently, power devices made of silicon carbide (SiC) have been developed. SiC is a wide-bandgap semiconductor, and has a breakdown field strength approximately 10 times as great as that of silicon (Basics and Application of SiC Elements, Kazuo Arai and Sadafumi Yoshida, pp. 165-185, Published by Ohmsha Ltd., Issued March 2003). In the field of semiconductor devices formed of SiC, a SiCMOSFET on the surface of which a MOS structure is formed has been developed, as in the case of silicon.
In a SiCMOSFET, however, resistivity of a p-body region is high. Further, the electric field tends to concentrate on an end portion of the p-body region. Therefore, there has been the problem that Voltage drop occurs in the p-body region during an avalanche breakdown and a parasitic bipolar transistor formed of a source region, a p-body region, and an n-base region operates. Moreover, since the temperature characteristics of this bipolar transistor are positive, a positive feedback occurs, and currents are concentrated on specific cells. This results in the problem that the temperature is locally elevated and specific cells are easily destroyed.